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LTC3858-1: Low IQ, Dual 2-Phase Synchronous Step-Down Controller Data Sheet12/2/2010PDF428K
Overview
Features and Benefits
- Low Operating IQ: 170μA (One Channel On)
- Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
- Wide VIN Range: 4V to 38V
- RSENSE or DCR Current Sensing
- Out-of-Phase Controllers Reduce Required Input Capacitance and Power Supply Induced Noise
- OPTI-LOOP® Compensation Minimizes COUT
- Phase-Lockable Frequency (75kHz-850kHz)
- Programmable Fixed Frequency (50kHz-900kHz)
- Selectable Continuous, Pulse-Skipping or Burst Mode® Operation at Light Loads
- Very Low Dropout Operation: 99% Duty Cycle
- Adjustable Output Voltage Soft-Start
- Power Good Output Voltage Monitor
- Output Overvoltage Protection
- Output Latch-Off Protection During Short Circuit
- Low Shutdown IQ: 8μA
- Internal LDO Powers Gate Drive from VIN or EXTVCC
- No Current Foldback During Start-Up
- Tiny 4mm × 5mm QFN and Narrow SSOP Packages
Product Details
The LTC3858-1 is a high performance dual step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows a phase-lockable frequency of up to 850kHz. Power loss and noise due to the input capacitor ESR are minimized by operating the two controller outputs out of phase.
The 170μA no-load quiescent current extends operating life in battery powered systems. OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3858-1 features a precision 0.8V reference and a power good output indicator. A wide 4V to 38V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries.
Independent soft-start pins for each controller ramp the output voltages during start-up. The output latch-off feature protects the circuit in short-circuit conditions.
For a leadless 32-pin QFN package with the additional features of adjustable current limit, clock out, phase modulation and two PGOOD outputs, see the LTC3858 data sheet.
| LTC3858 | LTC3858-1 | LTC3858-2 | |
| Features | Adjustable Current Limit, Clock Output, Phase Modulation, 2 PGOOD Outputs | Fixed Current Limit, One PGOOD Output | Overvoltage protection crowbar and short-circuit latchoff disabled |
| Package | QFN-32 | SSOP-28 | QFN-32 |
Applications
- Automotive Systems
- Battery Operated Digital Devices
- Distributed DC Power Systems
Product Lifecycle
Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Documentation & Resources
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R526 Reliability Data3/26/2018PDF365 K
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DC1352A - Demo Board10/22/2009PDF1M
Tools & Simulations
LTspice
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
LTC3858
LTC3858-1
LTC3858-2
LTpowerCAD
LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.
To open the project file for this circuit:
Step 1: Download and install LTpowerCAD on your computer.
Step 2: Click on the link(s) in the section below to download part-specific project files.
Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.
LTpowerCAD Project Files
Design tools for the following parts are available in LTpowerCAD:
LTC3858
LTC3858-1
LTC3858-2
Design Resources
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.
| Part Number | Material Declaration | Reliability Data | Pin/Package Drawing | CAD Symbols, Footprints & 3D Models |
|---|---|---|---|---|
| LTC3858EGN-1#PBF | Material Declaration | Reliability Data | 28-Lead SSOP (Narrow 0.15 Inch) | |
| LTC3858EGN-1#TRPBF | Material Declaration | Reliability Data | 28-Lead SSOP (Narrow 0.15 Inch) | |
| LTC3858EUFD-1#PBF | Material Declaration | Reliability Data | 28-Lead QFN (4mm x 5mm x 0.75mm w/ EP) | |
| LTC3858EUFD-1#TRPBF | Material Declaration | Reliability Data | 28-Lead QFN (4mm x 5mm x 0.75mm w/ EP) | |
| LTC3858IGN-1#PBF | Material Declaration | Reliability Data | 28-Lead SSOP (Narrow 0.15 Inch) | |
| LTC3858IGN-1#TRPBF | Material Declaration | Reliability Data | 28-Lead SSOP (Narrow 0.15 Inch) | |
| LTC3858IUFD-1#PBF | Material Declaration | Reliability Data | 28-Lead QFN (4mm x 5mm x 0.75mm w/ EP) | |
| LTC3858IUFD-1#TRPBF | Material Declaration | Reliability Data | 28-Lead QFN (4mm x 5mm x 0.75mm w/ EP) | |
| Wafer Fabrication Data | R526 Reliability Data |
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Lead Times
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Evaluation Boards
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.